Presently, to prepare for intrapartum fetal heart rate monitoring wherein the fetal amniotic membranes have not ruptured naturally, one must first perform an amniotomy, i.e. an artificially forced rupturing of the membranes. This must be done in order to provide the fetal electrode with clear, clean and direct access to the presenting part of the fetus.
It is therefore known to introduce into the birth canal, as a first and separate procedure, a barbed amniotic membrane perforator, such as the elongate plastic perforator sold under the trade name AMNIHOOK by Hollister Inc. of Libertyville, Ill. Finger cot amnio-hooks and other barbed perforator devices are also available. The perforator is dragged sideways across the fetal amniotic membranes so as to hook and rupture them. The perforator is then removed from the birth canal.
Next, it is also known, as a second and separate procedure, to introduce a spiral electrode into the birth canal and to screw it into the now-exposed fetal scalp, or into the epidermis of another fetal presenting part. This is accomplished by means of a curved introducer sleeve apparatus having a smooth-surfaced (non-barbed) external guide tube. The introducer sleeve is then removed from the birth canal. This leaves the electrode in place, which electrode is connected to an electrocardiogram-type recording device, or other sensing equipment, in order to allow intrapartum fetal heart rate monitoring.
Prior developments in this field may be generally illustrated by reference to the following information disclosure statement:
______________________________________ Pat. No. Patentee Issued ______________________________________ 3,827,428 Hon et al. Aug. 06, 1974 3,580,242 La Croix May 25, 1971 3,750,650 Ruttgers Aug. 07, 1973 3.472,234 Tachick Oct. 14, 1969 ______________________________________
Published articles which are of interest include: Hon et al., "Electronic Evaluation of Fetal Heart Rate", Vol. 40 Obstetrics and Gynecology, pp. 362 et seq. (September 1972); Paul et al., "Clinical Fetal Monitoring", Vol. 41 Obstetrics and Gynecology, pp. 777 et seq. (May 1973); and Fukushima et al., "An Improved Spiral Electrode Applicator System for Fetal Heart Rate Monitoring", Vol. 77 Obstetrics and Gynecology, pp. 475 et seq. (March 1991).
The first crude fetal scalp electrode was introduced about 1971 by George LaCroix. In 1973, Helge Ruttgers developed a double spiral electrode for fetal heart rate monitoring. Neither of these devices received widespread acceptance.
In 1974, Edward Hon developed the bipolar electrode and introducer sleeve which is described in U.S. Pat. No. 3,827,428 and which is currently the device most commonly used in this and other countries for internal fetal heart rate monitoring.
Currently, there are four million deliveries annually in the United States. About eighty per cent of these utilize fetal heart rate monitoring. Up to eighty or ninety per cent of the latter subgroup require amniotomies.
As noted above, where the membranes have not ruptured spontaneously, the Hon electrode cannot be applied without first performing, in a separate procedure, an amniotomy with another device. This is unfortunate because each birthing facility must order, inventory, stock, and quickly and reliably find, if and when needed, a membrane perforator for most deliveries where an electrode will be applied. Of course, the scalp electrode, including introducer sleeve apparatus, must be separately stocked and located. The need to stock two separate items effectively doubles the risk that a procedure will not be performed in a timely manner due to one of the items being misplaced, out of stock, accidentally rendered septic, or the like.
One of the most uncomfortable events for a patient in labor is the vaginal exam, which procedure involves penetration by instruments and/or the fingers of the attending practitioner. As noted, present practice involves two separate intrusions in order to attach the scalp electrode. The practitioner must do a vaginal exam to rupture the membranes, withdraw his hands from the vagina, change instruments and then re-enter the vagina to apply the electrode to the fetus.
Thus, patients would appreciate the decrease in discomfort that would result from combining these two procedures into one. Physicians would appreciate the savings in time and the increase in focus and control gained by such simplification. Not only would patients also appreciate the savings in time, but in cases where time is of the essence, such savings and simplification could provide significant benefits in health and safety, and result in fewer errors. Both the birthing facility and its patients would appreciate the savings in material and expense that would result from the elimination of one type of apparatus.